The current prior art is composed of an infinity of models of suction acoustic filters for reciprocating compressors. Generally, such suction filters comprise a chamber arranged between the fluid return pipeline of any system (such as, for example, a refrigeration system) and the suction inlet of the reciprocating compressor that composes that system.
As already known by the skilled in the art, the main functionality of these types of suction acoustic filters is the mitigation of part of the suction noise caused by the compressor. Thus, the chamber of the suction acoustic filters presents a volume that is capable of muffling the suction pulsations.
Consequently, it is noted that the volume of the chamber of a suction acoustic filter must be, in a certain way, pre-sized in accordance with the capability and applicability of each reciprocating compressor. In this sense, it is also considered the type of working fluid that will be compressed. Moreover, it is broadly known that the prior art provides several types of materials for manufacturing suction acoustic filters.
Conventionally, the suction acoustic filter suitable for reciprocating compressor is placed in the interior of the shell of the compressor, the inlet thereof being immediately next to the fluid return pipeline, and the outlet thereof being physically associated with the head of the compressor. Therefore, the chamber of the suction acoustic filter shall present a volume that is suitable for its operation, and, additionally, it cannot occupy a big area in the interior of the shell of the compressor.
A great part of the prior art suction acoustic filters is exclusively designed for reducing noises, and, in this case, other arrangements, that are incorporated or not into the compressor, are responsible for eliminating liquid fluids from the inlet of the suction of the compressor.
Thus, it shall be emphasized that the entrance of liquid-phase fluids in the suction chamber of the compressor extremely prejudices its operation, since liquids are not compressible. The compression of liquids results in very high pressure levels, which can cause the failure in the components of the compressor, reducing, therefore, the performance and the service life or, in a more extreme case, causing the critical failure in the compressor with total loss of operation.
Causes for the return of liquid to the compressor are assorted, and the major causes are related to failures in the design or in the use of the refrigeration system. Peculiarly, in refrigeration systems of commercial use, it is necessary to have a robust compressor to deal with the return of critical amounts of fluid, more specifically in two processes: flooded start and thaw of the evaporator (in refrigeration systems). In the flooded start, the compressor has its shell partially filled with the working fluid in the liquid phase, and the process of starting shall occur considering such severity. In the thaw of the evaporator, occurs the continuous pumping of the liquid to the compressor, due to the use of the overheated gas of the discharge of the compressor to thaw the evaporator, wherein the gas is liquefied and returns through the suction.
One example of the arrangement (placed outside from the suction acoustic filter) designed for reducing the liquid-phase fluid can be observed in document PCT/BR2010/000179, wherein it is revealed a suction pipeline whose inlet end for the fluid return presents a geometry that is capable of expelling part of the liquid-phase fluid.
In any case, the current prior art also provides suction acoustic filters whose constructivity is, in part, responsible for the retention of at least one portion of the working fluid in the liquid phase.
One example of this type of acoustic filter can be noted in document U.S. Pat. No. 6,547,032. The object of this document is further illustrated, for better clarifications, in FIG. 1 of the instant invention.
The filter illustrated in FIG. 1 (figure of document U.S. Pat. No. 6,547,032, but having the references altered) comprises a chamber that, among other aspects, comprises one inlet E, one outlet S, and one intermediate pipeline I. Thus, all the return fluid (suction fluid), whether in the liquid phase or in the gaseous phase, enters the acoustic filter through the inlet E, flows towards the bottom of the chamber through the intermediate pipeline I, and flows towards the outlet pipeline S. As the intermediate pipeline I is not interconnected to the outlet pipeline S, it can be considered that at least one portion of the liquid-phase fluid will be retained in the bottom of the chamber of the acoustic filter. However, this aspect is not mentioned in document U.S. Pat. No. 6,547,032, and, moreover, it is noted that, since the liquid-phase fluid occupies a certain volume of the chamber, the function of retaining liquids is almost non-existent.
Additionally, the inlet E of the acoustic filter of FIG. 1 (document U.S. Pat. No. 6,547,032) is inferior, resulting in the suction of a greater amount of liquid-phase fluid by the acoustic filter, since the inlet E is directed to the inferior region of the shell of the compressor which is conventionally filled with working fluid in the liquid phase.
In this sense, it shall be further mentioned that the current prior art already reveals models of suction acoustic filters whose inlet and outlet are directed to the superior region of the shell of the compressor, whose purpose is to deal with the flooded start process, capturing the gas above the liquid portion. One example of such assemblage is illustrated in FIG. 2 of the instant invention.
Although the above-mentioned solutions are robust against processes considering the suction of liquids, there is a decrease of the efficiency of the compressor during its normal operation. The gas that enters the suction passing part is not directly conducted to the inlet of the acoustic filter. Before reaching the inlet of the suction chamber, the gas gets in contact with the hot parts of the compressor, causing the heating and reduction of its specific mass, resulting in the decrease of mass flow, capability of refrigeration and performance. One solution to reduce the effects of the overheating, without losing its robustness against the suction of liquids, would be the generation of obstacles for the suction of liquids without prejudicing the suction of gas.
Thus, it is noted that the current solutions and designs of suction acoustic filters for reciprocating compressors do not provide concretizations that are especially dedicated to efficiently retain the working fluid in the liquid phase, and, with basis on this scenario, the present invention will be defined.